|Número de publicación||US4744418 A|
|Tipo de publicación||Concesión|
|Número de solicitud||US 06/939,660|
|Fecha de publicación||17 May 1988|
|Fecha de presentación||9 Dic 1986|
|Fecha de prioridad||27 Ene 1986|
|Número de publicación||06939660, 939660, US 4744418 A, US 4744418A, US-A-4744418, US4744418 A, US4744418A|
|Inventores||Robert D. Sydansk|
|Cesionario original||Marathon Oil Company|
|Exportar cita||BiBTeX, EndNote, RefMan|
|Citas de patentes (25), Otras citas (12), Citada por (35), Clasificaciones (15), Eventos legales (6)|
|Enlaces externos: USPTO, Cesión de USPTO, Espacenet|
This is a continuation-in-part application of copending application Ser. No. 822,709 filed on Jan. 27, 1986, now U.S. Pat. No. 4,683,944, which is a continuation-in-part application of application Ser. No. 807,416 filed on Dec. 10, 1985, now abandoned.
1. Technical Field
The invention relates to an oil recovery process and more particularly to a process of preparing a delayed polymer gel for oil recovery applications.
2. Description of Related Art
Polymer gels have potential application to a number of oil recovery processes including cementing, fracturing and conformance improvement. Poor vertical conformance results from the vertical juxtaposition of relatively high permeability geologic regions to relatively low permeability regions within a subterranean formation. Poor areal conformance results from the presence of high permeability streaks and high permeability anomalies within the formation matrix, such as vertical fractures and networks of the same, which have very high permeability relative to the formation matrix. Fluids generally exhibit poor flow profiles and sweep efficiencies in subterranean formations having poor vertical or areal conformance. Poor conformance is particularly a problem where vertical heterogeneity and/or fracture networks or other structural anomalies are in fluid communication with a subterranean wellbore across which fluids are injected or produced.
A number of attempts to remedy conformance problems exist. U.S. Pat. Nos. 3,762,476; 3,981,363; 4,018,286; and 4,039,029 to Gall or Gall et al describe various processes wherein gel compositions are formed in high permeability regions of subterranean formations to reduce the permeability therein. According to U.S. Pat. No. 3,762,476, a polymer such as polyacrylamide is injected into a formation followed sequentially by a crosslinking agent. The sequentially injected slugs are believed to permeate the treatment region of the formation and gel in situ.
It is generally held that effective polymer/crosslinking agent systems necessitate sequential injection of the gel components followed by in situ mixing because gel systems mixed on the surface are difficult to regulate. Systems mixed on the surface often gel at an excessive rate, forming gel balls before they can effectively penetrate the treatment region. However, in practice, conformance treatments such as that disclosed in U.S. Pat. No. 3,762,476 using sequentially injected gel systems have also proven unsatisfactory because of the inability to achieve complete mixing and gelation in the formation. As a result, gels only form at the interface of the unmixed gel components and often in regions remote from the desired treatment region. Likewise, processes employing sequentially injected gel systems for cementing and fracturing applications have proven unsatisfactory because the resulting gels do not have sufficient strength and integrity to withstand the stresses encountered in oil recovery processes.
A need exists for a gelation process wherein the gelation solution gels at a controllable, delayed rate, even at high temperatures. A need exists for a process wherein gelation of the polymer is substantially delayed until the gelation solution penetrates the desired treatment region of a subterranean hydrocarbon-bearing formation and sets up thereafter as an effective uniform gel. A need exists for a gelation process which can produce a range of versatile gels having the desired predetermined strengths and integrities for conformance-improving, cementing, or fracturing applications.
The present invention provides a process for improving hydrocarbon recovery from a subterranean hydrocarbon-bearing formation penetrated by a production and/or injection well. According to one embodiment, the process improves vertical and areal conformance in the formation and correspondingly improves flow profiles and sweep efficiencies of injected and/or produced fluids in the formation. According to another embodiment, the process provides a strong, permanent material for cementing jobs. According to yet another embodiment, the process provides an effective fluid for formation fracturing. These objectives and others are achieved by a polymer gelation process employing a polyvalent metal crosslinking agent and a high molecular weight, water-soluble polyacrylamide, which is substantially unhydrolyzed or has only a limited degree of hydrolysis.
The process comprises preparing a single aqueous gelation solution at the surface containing the polyacrylamide and the crosslinking agent. The resulting gelation solution is injected into a desired subterranean region where it gels to completion in situ. The present invention enables the practitioner to control the gelation rate or time required for complete gelation by limiting the degree of hydrolysis in the polyacrylamide. The degree of hydrolysis is selected according to the desired hydrocarbon recovery application, i.e., fracturing, cementing or conformance improvement, and the specific demands of the subterranean formation.
The resultant gel is a viscous continuous single-phase composition comprised of the polymer and crosslinking agent. Once the gel is in place for its desired function or backflushed in the case of formation fracturing, fluids may be injected into or produced from the hydrocarbon-bearing regions of the formation in fluid communication with the wellbore. The gel in place is substantially incapable of flowing from the treatment region and is substantially permanent and resistant to in situ degradation.
The process provides distinct advantages over known gelation processes. The practitioner of the present invention can fully prepare and mix a single gelation solution at the surface to achieve a controlled gelation rate. The practitioner predetermines a specific desired gelation rate by selecting the value of one relatively independent parameter, degree of hydrolysis in the polyacrylamide, without substantially altering the majority of gelation parameters. The resultant gel has sufficient strength and stability to meet the demands of the formation and the specific hydrocarbon recovery process employed.
Although the gelation rate can be predetermined by varying other gelation parameters as disclosed in copending U.S. application Ser. No. 822,709, controlling the degree of hydrolysis in the polyacrylamide may be economically and/or operationally more attractive. Since other gelation parameters are functionally correlated to final gel properties such as gel strength and stability, varying these parameters to achieve a given gelation rate could adversely effect the final gel properties. The present process allows one to set the gelation rate as a function of only one gelation parameter without substantially altering the final gel properties.
The present invention is especially applicable to the treatment of high temperature formations which are greater than 38° C. and in certain cases even greater than 100° C. As a rule, the gelation rate of a gelation solution increases with increasing temperature. The present invention enables one to sufficiently delay the gelation of a gelation solution, even in a high temperature formation, so that the solution can be placed in the treatment region before setting up.
FIGS. 1, 2 and 3 are graphs showing the functional relationship between the gelation rate and the degree of hydrolysis in the polyacrylamide.
The present invention is described in the context of specific terms which are defined as follows. The formation consists of two general regions, the "matrix" and "anomalies." An "anomaly" is a volume or void space in the formation having very high permeability relative to the matrix. It is inclusive of terms such as streaks, fractures, fracture networks, vugs, solution channels, caverns, washouts, cavities, etc. The "matrix" is substantially the remainder of the formation volume characterized as essentially homogeneous, continuous, sedimentary reservoir material free of anomalies and often competent.
The matrix consists of horizontal "zones" of distinctive subterranean material of continuous geologic properties which extend in the horizontal direction. "Vertical conformance" is a measure of the degree of geologic uniformity in permeability as one moves vertically across the formation. "Areal conformance" is a measure of the degree of geologic uniformity in permeability as one moves horizontally across the formation. A "flow profile" qualitatively describes the uniformity of fluid flow through a subterranean formation while "sweep efficiency" is the quantitative analog of "flow profile." "Plugging" is a substantial reduction in permeability in a region of a formation.
The term "gel" as used herein is directed to a continuous three-dimensional crosslinked polymeric network having an ultra high molecular weight. The gel contains a liquid medium such as water which is confined within the solid polymeric network. The fusion of a liquid and a solid component into a single-phase system provides the gel with a unique phase behavior. Gels employed by the present invention have sufficient structure so as not to propagate from the confines of a plugged region into a less permeable region of the formation adjoining the plugged region once in place.
The gel is qualitatively defined as "flowing" or "non-flowing" based on its ability to flow under the force of gravity when unconfined on the surface at ambient atmospheric conditions. A flowing gel flows under these conditions; a non-flowing gel does not. Nonetheless, both a non-flowing gel and a flowing gel are defined herein as having sufficient structure so as not to propagate from the confines of the desired treatment region when injected therein.
"Partially gelled" solutions are also referred to herein. A partially gelled solution is at least somewhat more viscous that an uncrosslinked polymer solution such that it is incapable of entering a less permeable region where no treatment is desired, but sufficiently fluid such that it is capable of displacement into a desired treatment zone. The crosslinking agent of the partially gelled solution has reacted incompletely with the polymer with the result that neither all of the polymer nor all of the crosslinking agent in the gelation solution is totally consumed by the crosslinking reaction. The partially gelled solution is capable of further crosslinking to completion resulting in the desired gel without the addition of more crosslinking agent.
"Crosslinked to completion" means that the gel composition is incapable of further crosslinking because one or both of the required reactants in the initial solution are consumed. Further crosslinking is only possible if either polymer, crosslinking agent, or both are added to the gel composition.
The term "polyacrylamide", when used without qualification, generally encompasses both partially hydrolyzed and substantially unhydrolyzed acrylamide polymers. However, the "polyacrylamide" employed in the present invention is qualified as having no more than a limited degree of hydrolysis, i.e., substantially unhydrolyzed (defined as less than 1% hydrolyzed) or having only a limited degree of hydrolysis. Thus, the polyacrylamide of the present invention has less than about 5.0% of the amide groups hydrolyzed to carboxylate groups, preferably less than about 3.5%, and most preferably less than about 1.0%. At extremely high temperature, it may even be preferable to employ a polyacrylamide having less than about 0.1% of the amide groups hydrolyzed to carboxylate groups.
The polyacrylamide may be prepared according to any conventional method known in the art, but preferably has the specific molecular weight characteristics of the polyacrylamide prepared according to the method disclosed by U.S. patent Re. 32,114 to Argabright et al incorporated herein by reference. The average molecular weight of the polyacrylamide is in the range of about 10,000 to about 50,000,000 and preferably about 100,000 to about 20,000,000, and most preferably about 200,000 to about 15,000,000. The polymer concentration in the solution is about 500 ppm up to the solubility limit of the polymer in the solvent or the rheological constraints of the polymer solution and preferably about 10,000 to about 80,000 ppm.
The gel composition utilized in the present invention comprises the polyacrylamide characterized above and a polyvalent metal crosslinking agent. The polyvalent metal crosslinking agent is defined as a polyvalent metal cation ionized or complexed in an aqueous solution which is capable of crosslinking the polymer. Exemplary polyvalent metal cations useful in the practice of the present invention include Ca2+, Mg2+, Ba2+, Zn2+, Sn2+, Al3+, Fe3+, Cr3+, Ti4+, Zr4+, etc. The crosslinking agent is prepared by dissolving an organic or inorganic salt of the appropriate polyvalent metal in the aqueous solvent.
A preferred crosslinking agent of the present invention includes at least one or more electropositive chromium II species. The chromium III species is complexed with one or moe electronegative carboxylate species. The complex may advantageously also contain one or more electronegative hydroxide and/or oxygen species. It is believed that, when two or more chromium III species are present in the complex, the oxygen or hydroxide species may help to bridge the chromium III species. Each complex optionally contains additional species which are not essential to the polymer crosslinking function of the complex. For example, inorganic mono- and/or divalent ions, which function merely to balance the electrical charge of the complex, or one or more water molecules may be associated with each complex. Representative formulae of such complexes include:
[Cr3 (CH3 CO2)6 (OH)2 ]+1 ;
[Cr3 (OH)2 (CH3 CO2)6 ]NO3.6H2 O;
[Cr3 (H2 O)2 (CH3 CO2)6 ]+3 ;
[Cr3 (H2 O)2 (CH3 CO2)6 ](CH3 CO2)3.H2 O; etc.
Trivalent chromium and chromic ion are equivalent terms encompassed by the term chromium III species as used herein. The carboxylate species are advantageously derived from water-soluble salts of carboxylic acids, especially low molecular weight mono-basic acids. Carboxylate species derived from salts of formic, acetic, propionic, and lactic acid, lower substituted derivatives thereof and mixtures thereof are especially preferred. The carboxylate species include the following water-soluble species: formate, acetate, propionate, lactate, lower substituted derivatives thereof, and mixtures thereof. The optional inorganic ions include sodium, sulfate, nitrate and chloride ions.
A host of complexes of the type described above and their method of preparation are well known in the leather tanning art. These complexes are described in Shuttleworth and Russel, Journal of The Society of Leather Trades' Chemists, "The Kinetics of Chrome Tannage Part I.," United Kingdom, 1965, v. 49, p. 133-154; "Part III.," United Kingdom, 1965, v. 49, p. 251-260; "Part IV.," United Kingdom, 1965, v. 49, p. 261-268; and Von Erdman, Das Leder, "Condensation of Mononuclear Chromium (III) Salts to Polynuclear Compounds," Eduard Roether Verlag, Darmstadt, Germany, 1963, v. 14, p. 249; and are incorporated herein by reference. Udy, Marvin J., Chromium, Volume 1: Chemistry of Chromium and its Compounds, Reinhold Publishing Corp., N.Y., 1956, pp. 229-233; and Cotton and Wilkinson, Advanced Inorganic Chemistry 3rd Ed., John Wiley & Sons, Inc., N.Y., 1972, pp. 836-839, further describe typical complexes which may be within the scope of the present invention and are incorporated herein by reference.
The gel is formed by admixing the polymer and crosslinking agent at the surface to form a single injectable gelation solution. Surface admixing broadly encompasses inter alia mixing the solution in bulk at the surface prior to injection or simultaneously mixing the solution at or near the wellhead by in-line mixing means while injecting it. The weight ratio of polymer to crosslinking agent is about 1:1 to 500:1, preferably about 2.5:1 to 200:1, and most preferably about 5:1 to 50:1.
The aqueous solvent of the gelation solution may be fresh water or a brine having a total dissolved solids concentration up to the solubility limit of the solids in water. Inert fillers such as crushed or naturally fine rock material or glass beads can also be added to the gelation solution to reinforce the gel network structure.
The present process enables the practitioner to produce a gel at a predetermined gelation rate as a function of the degree of polymer hydrolysis. The gelation rate is defined as the degree of gel formation as a function of time or, synonymously, the rate of crosslinking in the gelation solution. The degree of crosslinking may be quantified in terms of gel viscosity and/or strength.
The gelation rate of the gelation solution generally decreases as the degree of polymer hydrolysis decreases. However, the effect is generally observed when the degree of polymer hydrolysis is below a maximum or threshold level. The actual value of the maximum is usually not more that 7%, but may be less than that value, depending on the other fixed gelation parameters. Above the maximum value, the gelation rate appears to be relatively insensitive to varying the degree of polymer hydrolysis.
The practitioner advantageously selects a predetermined gelation rate which enables preparation of the gelation solution at the surface, injection of the solution as a single uniform slug into the wellbore, and displacement of the entire solution into the desired subterranean zone. Once in place in the desired treatment region, gelation of the solution advantageously proceeds to achieve substantially complete gelation of the solution in situ.
The present gelation mechanism enables the practitioner to design a gelation solution which can be injected into a treatment region at a desired injection rate with little resistance to injectivity. The solution is preferably gelled rapidly after it is in place in the desired subterranean region to minimize lost production from shut in of injection and/or product wells.
The present process is particularly applicable to cases where it is extremely difficult to prepare a polymer gelation solution having a favorable gelation rate under formation conditions. For example, formation temperatures as low as 38° C. at the depth of the treatment region can cause premature gelation of a polymer gelation solution in the wellbore and subsequent undesired plugging of portions of the formation, wellbore, or wellbore face. By employing a polyacrylamide having no more than a limited degree of hydrolysis in the gelation solution, gelation can be delayed to a sufficient degree which enables the solution to be placed in a high temperature treatment region while the gel is still mobile.
The process is also applicable to cases where specific crosslinking agents, such as chromic chloride or chromic nitrate, gel conventional partially hydrolyzed polyacrylamide (PHPA), i.e., about 30% hydrolyzed, at uncontrollably rapid rates even at temperatures below 38° C. Uncontrolled crosslinking can result in the formation of local gel balls around the crosslinking agent as it is added to the polymer solution, which prevents effective mixing and continuous gel formation. Substitution of the PHPA with a polyacrylamide having no more than a limited degree of hydrolysis enables one to produce a uniform gel at a controlled rate with the same previously ineffective crosslinking agent.
The gelation rate can generally be delayed such that complete gelation does not occur for up to about 24 hours or more from the time the gelation solution is formulated and injected using the present process. Even under extremely unfavorable in situ conditions, the gelation rate can be delayed such that complete gelation does not occur for at least 1 to 48 hours or more and preferably at least 6 to 24 hours by careful formulation of the gel.
The present process is applicable to a number of hydrocarbon recovery applications. According to one embodiment, the process is applicable to conformance treatment of formations under most conditions and is specific to treating regions within the formation which are in fluid communication with an injection or production well. The flowing gel is especially applicable to the treatment of anomalies such as streaks of relatively high permeability, fractures or fracture networks in direct communication via the anomaly with an injection well but not also in direct communication via the anomaly with a production well. The ultimate gel is termed a flowing gel as defined herein because it would flow if unconfined on the surface. However, the flowing gel is sufficiently crosslinked to remain in place under injection conditions in the anomaly when confined thereby. Thus, the flowing gel is capable of effectively plugging the anomaly.
The flowing gel is not generally suitable for treatment of anomalies in direct communication via the anomaly with production wells because flowing gels do not have sufficient strength to withstand the drawdown pressure during production and may flow back into the wellbore. For treatment of anomalies in direct communication with production wells, non-flowing rigid gels having sufficient strength to withstand the production drawdown pressure are preferred. It is preferred that substantially none of the gel flows back into the wellbore when oil is produced after the conformance treatment.
In some specialized cases, the solution can be injected into a selected high permeability zone of the matrix and crosslinked to completion in situ as either a non-flowing gel or a flowing gel. Both flowing and non-flowing gels can be used for treatment of high permeability zones of the matrix because in general neither will flow from the treatment zone upon complete gelation, a necessary condition for the present invention. However, non-flowing gels are often preferred for treatment of high permeability zones in direct communication with production wells because of their increased strength.
Conformance treatment of regions in direct communication with a production well by the process of the present invention can effectively improve the hydrocarbon productivity of the well and/or decrease the water to hydrocarbon ratio of the produced fluids.
According to another embodiments, the present process is applicable to cementing and fracturing operations. The gelation solution is prepared in the manner described above and applied according to conventional cementing or fracturing methods known in the art. The non-flowing rigid gel produced according to the present invention is the preferred cement composition for cementing jobs. The composition is particularly applicable to remedial squeeze-cementing jobs which can also effectively improve the hydrocarbon productivity of a production well and/or decrease the water to hydrocarbon ratio of the produced fluids. The cement composition is also applicable to plugging abandoned wells. The flowing gel produced according to the present invention is the preferred fracturing fluid.
The following examples demonstrate the practice and utility of the present invention but are not to be construed as limiting the scope thereof.
Most of the examples are formatted as tables of data which describe the formulation and maturation of one or more gels. Each gel is represented in a table by a single experimental run. Data include the conditions for producing the gel and the quantitative or qualitative strength of the produced gel. The tables display data in a three-tier format. The first tier is the values of the fixed gelation conditions which are constant and common to every run in the table. The second tier is values of the gelation conditions which vary among the different runs in the table but are constant for any given run. The third tier is the gel strength which varies as a function of time within each run. Qualitative gel strength is expressed in alphabetic code. Quantitative gel strength is simply the numerical value of apparent viscosity.
The following gel strength code and nomenclature are useful for interpreting the tables.
A. No detectable continuous gel formed: the bulk of the gelation solution appears to have the same viscosity as the original polymer solution although in some cases isolated highly viscous gel balls may be present.
B. Highly flowing gel: the gel appears to be only slightly more viscous than the initial polymer solution.
C. Flowing gel: most of the gel flows to the bottle cap by gravity upon inversion.
D. Moderately flowing gel: only a small portion (5-10%) of the gel does not readily flow to the bottle cap by gravity upon inversion (usually characterized as a tonguing gel).
E. Barely flowing gel: the gel can barely flow to the bottle cap and/or a significant portion (>15%) of the gel does not flow by gravity upon inversion.
F. Highly deformable nonflowing gel: the gel does not flow to the bottle cap by gravity upon inversion.
G. Moderately deformable nonflowing gel: the gel deforms about half way down the bottle by gravity upon inversion.
H. Slightly deformable nonflowing gel: only the gel surface slightly deforms by gravity upon inversion.
I. Rigid gel: there is no gel surface deformation by gravity upon inversion.
J. Ringing rigid gel: a tuning fork-like mechanical vibration can be felt upon tapping the bottle.
Crosslinking Agent: Polyvalent metal salt used in preparation of ionized or complexed crosslinking agent.
% Hydrolysis: % of carboxylate groups on the polyacrylamide molecule based on the total number of amide groups
Polymer MW: average molecular weight of the polyacrylamide
Polymer Conc: polyacrylamide concentration in the polymer solution (ppm)
Polymer pH: pH of the polymer solution
Total Ion Conc: total concentration of crosslinking agent ions in the gelation solution (ppm)
Weight Ratio Polymer:Ions: weight ratio of polyacrylamide to crosslinking agent ions in the gelation solution
Metal Ion Conc: polyvalent metal cation concentration in the gelation solution
Temp: gelation temperature (°C.)
Time: gelation time (hr)
Gel Code: gel strength code
Viscosity: apparent viscosity of the gelation solution (cp)
Pressure: viscometer pressure (kPa)
The polymer solutions of the following examples are prepared by diluting aqueous polyacrylamide solutions with a fresh water solvent, i.e., Denver tap water. Where qualitative data are obtained, the dilute polymer solution is combined with a crosslinking agent solution in a 0.12 liter widemouth bottle to form a 0.05 liter sample. The sample is gelled in the capped bottle and the qualitative gel strength is determined by periodically inverting the bottle.
Where quantitative data are obtained, the polymer solution and crosslinking agent solution are combined in a variable pressure and temperature rheometer (viscometer), having an oscillatory mode of 0.1 rad/sec and 100% strain. The apparent viscosity at a shear rate of about 0.1 sec-1 is recorded as a function of time.
______________________________________Crosslinking Agent: Al2 (SO4)3% Hydrolysis: 0.6Polymer MW: 5,000,000Polymer Conc: 20,000Polymer pH: 6.0Temp: 60______________________________________ Run Number 1 2 3 4______________________________________Weight Ratio 3 9 27 81Polymer:IonsTime Gel Code0. C C C C0.25 C C C C0.50 C C D D1.0 C C D D2.0 C C D D3.0 C C D D4.0 C C D D5.0 C C D D6.0 C C E D7.0 C C E D24 C D F H48 D E G H72 D F H H96 D G H H168 D H I I300 D H I I600 D H I I______________________________________
______________________________________Crosslinking Agent: AlCl3% Hydrolysis: 0.6Polymer MW: 5,000,000Polymer Conc: 20,000Polymer pH: 6.0Temp: 22______________________________________ Run Number 1 2 3 4______________________________________Weight Ratio 3 9 27 81Polymer:IonsTime Gel Code0. A A A A0.25 A A A A0.50 C C C C1.0 C C C C2.0 C D E E3.0 C G F F4.0 C G H F5.0 C H H F6.0 C H H F7.0 C H H F24 C H I H48 D H I H96 E I I I192 E I I I432 E I I I______________________________________
______________________________________Crosslinking Agent: Al(NO3)3% Hydrolysis: 0.6Polymer MW: 5,000,000Polymer Conc: 20,000Polymer pH: 6.0Temp: 22______________________________________ Run Number 1 2 3 4______________________________________Weight Ratio 3 9 27 81Polymer:IonsTime Gel Code0. A A A A0.25 A A A A0.50 D E E C1.0 D E G C2.0 D F F D3.0 E G H E4.0 E H I E5.0 E H I F6.0 E H I F7.0 F H I G24 F I I G48 F I I G96 F I I G192 F I I G432 F I I G______________________________________
______________________________________Crosslinking Agent: acidic ZrAc2% Hydrolysis: 0.6Polymer MW: 5,000,000Polymer Conc: 20,000Polymer pH: 6.0Temp: 22______________________________________ Run Number 1 2 3 4______________________________________Weight Ratio 3 9 27 81Polymer:IonsTime Gel Code0. A A A A0.25 E E E C0.50 F F E C1.0 G H F C2.0 H I F C3.0 I I G C4.0 I I H C5.0 I I H C6.0 I I I D7.0 I I I D24 I I I E48 I I I E96 I I I E192 I I I F432 I J I F______________________________________
______________________________________Crosslinking Agent: Cr(NO3)3% Hydrolysis: 0.6Polymer MW: 5,000,000Polymer Conc: 20,000Polymer pH: 6.0Temp: 22______________________________________ Run Number 1 2 3 4______________________________________Weight Ratio 3 9 27 81Polymer:IonsTime Gel Code0. A A A A0.25 C C C C0.50 E F F E1.0 F H H G2.0 H H I H3.0 H H I H4.0 H I I H5.0 H I I I6.0 H I I I7.0 H I I I24 H I J I48 I I J I96 I I J I192 I I J I432 I I J I______________________________________
______________________________________Crosslinking Agent: CrCl3% Hydrolysis: 0.6Polymer MW: 5,000,000Polymer Conc: 20,000Polymer pH: 6.0Temp:______________________________________ Run Number 1 2 3 4______________________________________Weight Ratio 3 9 27 81Polymer:IonsTime Gel Code0. A A A A0.25 C C C C0.50 D E F E1.0 E H H H2.0 F H I I3.0 F H I I4.0 G H I I5.0 G I I I6.0 G I I I7.0 G I I I24 H I J I48 H I J I96 I I J I192 I I J I432 I I J I______________________________________
______________________________________Crosslinking Agent: CrAc3% Hydrolysis: 0.6Polymer MW: 5,000,000Polymer Conc: 20,000Polymer pH: 6.0Temp: 22______________________________________ Run Number 1 2 3 4______________________________________Weight Ratio 3 9 27 81Polymer:IonsTime Gel Code0. B A A A0.25 D A A A0.50 E C A A1.0 E C B A2.0 E C C B3.0 F C C B4.0 F D C C5.0 F E D C6.0 F E D C7.0 F E D C24 G G G F48 H H H H96 H H H H192 I I I I432 I I I I______________________________________
__________________________________________________________________________ % Hydrolysis: 30 Polymer MW: 5,000,000 Polymer Conc: 20,000 Polymer pH: 7.0 Temp: 22__________________________________________________________________________ Run Number 1 2 3 4 5 6 7__________________________________________________________________________Crosslinking Al2 (SO4)3 AlCl3 Al(NO3)3 CrCl3 Cr(NO3)3 CrAc3 ZrAc2AgentWeight Ratio 27 27 27 27 27 27 27Polymer:IonsTime Gel Code0. A A A A A A A0.25 A A A A A A A0.50 A A A A A A A1.0 A A A A A A A2.0 A A A A A B A3.0 A A A A A C A4.0 A A A A A D A24 A A A A A G A96 A A A A A I A168 A A A A A J A336 A A A A A J A__________________________________________________________________________
Local gel balls prevent continuous gel formation in Runs 1-5, 7 and 8.
The results of Examples 1-7 indicate the use of a polyacrylamide having a limited degree of hydrolysis according to the present invention enables effective delayed continuous gel formation with polyvalent metal crosslinking agents. By comparison, Example 8 using 30% hydrolyzed polyacrylamide and the same crosslinking agents produces undesirable gel balls rather than continuous gels in almost every case due to rapid uncontrolled gelation.
______________________________________Crosslinking Agent: CrAc3Polymer MW: 11,000,000Polymer Conc: 12,500Temp: 40Weight Ratio Polymer:Ions: 20Pressure: 3400______________________________________ Run Number 1 2______________________________________% Hydrolysis 30 <1Polymer pH 10 9Time Viscosity0 190,000 8,0000.1 255,000 10,0000.5 300,000 15,0001 350,000 25,0002 415,000 40,0003 460,000 70,0004 500,000 100,0008 575,000 210,00011 600,000 300,00014 605,000 355,00018 605,000 425,00020 605,000 460,00036 605,000 610,000______________________________________
FIG. 1 is a graphical representation of the data of Example 9.
______________________________________Crosslinking Agent: CrAc3Polymer MW: 5,000,000Polymer Conc: 10,000Polymer pH: 8.0Temp: 22Metal Ion Conc: 207Total Ion Conc: 990Weight Ratio Polymer:Ions: 10______________________________________ Run Number 1 2______________________________________% Hydrolysis: 30 <1Time Gel Code0.25 B A2.0 B A3.0 C A4.0 C A5.0 C B8.0 E B23 F B48 E B72 F B103 F B268 G B______________________________________
The data of Examples 9 and 10 show that the rate of gelation of 30% hydrolyzed polyacrylamide is considerably faster than that of polyacrylamide having a degree of hydrolysis below 1%. The data support the operability of the present invention.
______________________________________Crosslinking Agent: CrAc3Polymer MW: 5,000,000Polymer Conc: 20,000Temp: 22Metal Ion Conc: 225Weight Ratio Polymer:Ions: 20______________________________________ Run Number 1 2 3______________________________________% Hydrolysis <0.1 2.5 30Time Gel Code0.5 A C C1.0 A F E2.0 A G F3.0 A H G4.0 A I I5.0 A J I6.0 A J J7.0 A J J24 A J J48 A J J96 A J J168 A J J300 A J J672 A J J1680 A J J______________________________________
Example 11 shows the functional relation between the degree of hydrolysis in the polyacrylamide and the gelation rate. The gelation rate increases as the degree of hydrolysis increases up to a maximum which is about 2.5% in the present case.
FIGS. 2 and 3 are quantitative representations of the same functional relationship shown qualitatively in Examples 10 and 11. The crosslinking conditions in FIGS. 2 and 3 are the same as Example 11 with the following exceptions. The temperature of FIG. 2 is 100° C. and the temperature of FIG. 3 is 110° C. The polymer in FIG. 2 has a molecular weight of 5,000,000 and the polymer of FIG. 3 has a molecular weight of 11,000,000. In both cases, the gelation solutions are gelled at about 3400 kPa under anaerobic conditions.
The results of FIGS. 2 and 3 indicate the present invention is effective even in relatively high temperature formations.
While the foregoing preferred embodiments of the invention have been described and shown, it is understood that alternatives and modifications, such as those suggested and others, may be made thereto and follow in the scope of the invention.
|Patente citada||Fecha de presentación||Fecha de publicación||Solicitante||Título|
|US32114 *||23 Abr 1861||Railroad chair and splice|
|US2248028 *||9 Jun 1938||1 Jul 1941||Dow Chemical Co||Treatment of wells|
|US3114651 *||22 Jul 1960||17 Dic 1963||American Cyanamid Co||Water insolubilization of acrylamido polymers with a salt of trivalent chromium|
|US3302717 *||26 Dic 1961||7 Feb 1967||Dow Chemical Co||Selective plugging of subterranean formations to inhibit intrusion of water|
|US3306870 *||1 Jun 1964||28 Feb 1967||Dow Chemical Co||Fluid gelable composition of acrylamide polymers and aqueous solutions of inorganic hydroxides and salts|
|US3383307 *||30 Jul 1964||14 May 1968||Ashland Oil Inc||Gelling agents, gels and methods for forming gels|
|US3504746 *||19 Jun 1968||7 Abr 1970||Gaf Corp||Method of sealing a walled system with polyvinyl pyrrolidone|
|US3658129 *||1 Sep 1970||25 Abr 1972||Phillips Petroleum Co||In situ gelation of polymers during waterflooding|
|US3749172 *||9 Feb 1972||31 Jul 1973||Phillips Petroleum Co||Methods of using gelled polymers in the treatment of wells|
|US3762476 *||3 Ene 1972||2 Oct 1973||Phillips Petroleum Co||Subterranean formation permeability correction|
|US3833061 *||27 Dic 1972||3 Sep 1974||Phillips Petroleum Co||Method for selectively reducing brine permeability in a subterranean oil-wet formation|
|US3926258 *||12 Feb 1974||16 Dic 1975||Phillips Petroleum Co||Method for reducing formation permeability with gelled polymer solution having delayed gel time|
|US3938594 *||8 Abr 1974||17 Feb 1976||Marathon Oil Company||Fracturing fluid|
|US3949811 *||19 Abr 1974||13 Abr 1976||Phillips Petroleum Company||Method for reducing the permeability of subterranean formations to brines|
|US3978928 *||14 Abr 1975||7 Sep 1976||Phillips Petroleum Company||Process for the production of fluids from subterranean formations|
|US3981363 *||6 Nov 1975||21 Sep 1976||Phillips Petroleum Company||Partially crosslinked polymer used in correcting subterranean formation permeability|
|US4018286 *||6 Nov 1975||19 Abr 1977||Phillips Petroleum Company||Controlled well plugging with dilute polymer solutions|
|US4039029 *||6 Nov 1975||2 Ago 1977||Phillips Petroleum Company||Retreatment of wells to reduce water production|
|US4069869 *||11 Feb 1977||24 Ene 1978||Union Oil Company Of California||Plugging high permeability zones of reservoirs having heterogeneous permeability|
|US4193453 *||26 Jul 1978||18 Mar 1980||Standard Oil Company (Indiana)||Method for consolidating sand or water control in subterranean formations|
|US4488601 *||29 Sep 1982||18 Dic 1984||The Standard Oil Company||Control of aluminum cross-linked polyacrylamides for sweep improvement|
|US4498539 *||16 Nov 1983||12 Feb 1985||Phillips Petroleum Company||Selective plugging of highly permeable subterranean strata by in situ _gelation of polymer solutions|
|US4606407 *||29 Nov 1984||19 Ago 1986||Mobil Oil Corporation||Programmed gelation of polymers for oil reservoir permeability control|
|US4644073 *||11 Mar 1985||17 Feb 1987||Phillips Petroleum Company||Permeability contrast correction employing a sulfate-free propionate-sequestered chromium (III) solution|
|US4683949 *||27 Ene 1986||4 Ago 1987||Marathon Oil Company||Conformance improvement in a subterranean hydrocarbon-bearing formation using a polymer gel|
|1||*||Cotton and Wilkinson, Advanced Inorganic Chemistry 3rd Ed., John Wiley & Sons, Inc., N.Y., 1972, pp. 836 839.|
|2||Cotton and Wilkinson, Advanced Inorganic Chemistry 3rd Ed., John Wiley & Sons, Inc., N.Y., 1972, pp. 836-839.|
|3||*||Shuttleworth and Russel, Journal of the Society of Leather Trade s Chemists, Part III., United Kingdom, 1965, vol. 49, pp. 251 260.|
|4||Shuttleworth and Russel, Journal of the Society of Leather Trade's Chemists, "Part III.," United Kingdom, 1965, vol. 49, pp. 251-260.|
|5||Shuttleworth and Russel, Journal of the Society of Leather Trades' Chemists, "Part IV.," United Kingdom, 1965, vol. 49, pp. 261-268.|
|6||Shuttleworth and Russel, Journal of the Society of Leather Trades' Chemists, "The Kinetics of Chrome Tannage Part I., " United Kingdom, 1965, vol. 49, pp. 133-154.|
|7||*||Shuttleworth and Russel, Journal of the Society of Leather Trades Chemists, Part IV., United Kingdom, 1965, vol. 49, pp. 261 268.|
|8||*||Shuttleworth and Russel, Journal of the Society of Leather Trades Chemists, The Kinetics of Chrome Tannage Part I., United Kingdom, 1965, vol. 49, pp. 133 154.|
|9||*||Udy, Marvin J., Chromium, vol. 1: Chemistry of Chromium and Its Compounds, Reinhold Publishing Corp., N.Y., 1956, pp. 229 233.|
|10||Udy, Marvin J., Chromium, vol. 1: Chemistry of Chromium and Its Compounds, Reinhold Publishing Corp., N.Y., 1956, pp. 229-233.|
|11||Von Erdman, "Condensation of Mononuclear Chromium (III) Salts to Polynuclear Compounds," Das Leder, Eduard Roether Verlag, Darmstadt, Germany, 1963, vol. 14, pp. 249-266.|
|12||*||Von Erdman, Condensation of Mononuclear Chromium (III) Salts to Polynuclear Compounds, Das Leder, Eduard Roether Verlag, Darmstadt, Germany, 1963, vol. 14, pp. 249 266.|
|Patente citante||Fecha de presentación||Fecha de publicación||Solicitante||Título|
|US4842071 *||7 Mar 1988||27 Jun 1989||Institut Francais Du Petrole||Process for the selective reduction of water inflows in oil or gas producing wells|
|US4957166 *||11 Oct 1989||18 Sep 1990||Marath Oil Company||Lost circulation treatment for oil field drilling operations|
|US4973410 *||29 Nov 1989||27 Nov 1990||Air Products And Chemicals, Inc.||Crosslinked vinylamine polymer in enhanced oil recovery|
|US4974677 *||16 Oct 1989||4 Dic 1990||Mobil Oil Corporation||Profile control process for use under high temperature reservoir conditions|
|US4989673 *||14 Jul 1989||5 Feb 1991||Marathon Oil Company||Lost circulation fluid for oil field drilling operations|
|US4995461 *||24 Oct 1989||26 Feb 1991||Marathon Oil Company||Well kill treatment for oil field wellbore operations|
|US5069281 *||5 Nov 1990||3 Dic 1991||Marathon Oil Company||Process for enhanced delayed in situ gelation of chromium polyacrylamide gels|
|US5133408 *||31 May 1991||28 Jul 1992||Marathon Oil Company||Rate controllable gel for conformance improvement treatment in a subterranean hydrocarbon-bearing formation|
|US5219476 *||4 Mar 1992||15 Jun 1993||Eniricerche S.P.A.||Gellable aqueous composition and its use in enhanced petroleum recovery|
|US5547025 *||14 Abr 1995||20 Ago 1996||Phillips Petroleum Company||Process for treating oil-bearing formation|
|US5642783 *||17 May 1996||1 Jul 1997||Phillips Petroleum Company||Process for treating oil-bearing formation|
|US5663123 *||1 Feb 1995||2 Sep 1997||Kb Technologies Ltd.||Polymeric earth support fluid compositions and method for their use|
|US5849674 *||15 Oct 1996||15 Dic 1998||Phillips Petroleum Company||Compositions and processes for oil field applications|
|US6016869 *||31 Oct 1997||25 Ene 2000||Burts, Jr.; Boyce D.||Well kill additive, well kill treatment fluid made therefrom, and method of killing a well|
|US6016871 *||31 Oct 1997||25 Ene 2000||Burts, Jr.; Boyce D.||Hydraulic fracturing additive, hydraulic fracturing treatment fluid made therefrom, and method of hydraulically fracturing a subterranean formation|
|US6016879 *||31 Oct 1997||25 Ene 2000||Burts, Jr.; Boyce D.||Lost circulation additive, lost circulation treatment fluid made therefrom, and method of minimizing lost circulation in a subterranean formation|
|US6098712 *||31 Oct 1997||8 Ago 2000||Bottom Line Industries, Inc.||Method of plugging a well|
|US6102121 *||31 Oct 1997||15 Ago 2000||BottomLine Industries, Inc.||Conformance improvement additive, conformance treatment fluid made therefrom, method of improving conformance in a subterranean formation|
|US6166103 *||21 Dic 1998||26 Dic 2000||Atlantic Richfield Company||Aqueous gelable compositions with delayed gelling times|
|US6218343||31 Oct 1997||17 Abr 2001||Bottom Line Industries, Inc.||Additive for, treatment fluid for, and method of plugging a tubing/casing annulus in a well bore|
|US6248697||12 Feb 1998||19 Jun 2001||Kb Technologies, Ltd.||Composition and method for a dual-function soil-grouting excavating or boring fluid|
|US6716798||22 Abr 1999||6 Abr 2004||Burts Jr Boyce D||Conformance improvement additive, conformance treatment fluid made therefrom, method of improving conformance in a subterranean formation|
|US6897186||13 Jun 2001||24 May 2005||Kg International, Llc||Composition and method for dual function soil grouting excavating or boring fluid|
|US7281579||9 Dic 2002||16 Oct 2007||Aqueolic Canada Ltd.||Method for terminating or reducing water flow in a subterranean formation|
|US7347263||25 Feb 2005||25 Mar 2008||University of Pittsburgh - of the Commonwealth of Higher Education||Networked polymeric gels and use of such polymeric gels in hydrocarbon recovery|
|US7677313||13 Sep 2005||16 Mar 2010||Alberta Science And Research Authority||Method for controlling water influx into wellbores by blocking high-permeability channels|
|US8247488 *||21 Oct 2010||21 Ago 2012||Ripi||Modified polyacrylamide hydrogel|
|US8822388||28 Nov 2006||2 Sep 2014||Spi Technologies Llc||Multi-component aqueous gel solution for control of delayed gelation timing and for resulting gel properties|
|US20010049403 *||7 May 1999||6 Dic 2001||Boyce D. Burts, Jr.||Well kill additive, well kill treatment fluid made therefrom, and method of killing a well|
|US20050178544 *||9 Dic 2002||18 Ago 2005||Thomas Forast B.||Method for terminating or reducing water flow in a subterranean formation|
|US20050194145 *||25 Feb 2005||8 Sep 2005||Beckman Eric J.||Networked polymeric gels and use of such polymeric gels in hydrocarbon recovery|
|US20120279727 *||6 May 2011||8 Nov 2012||Clearwater International, Llc||Enhancing delaying in situ gelation of water shutoff systems|
|WO1989007698A1 *||28 Nov 1988||24 Ago 1989||Marathon Oil Co||Delayed in situ crosslinking of acrylamide polymers for oil recovery applications in high-temperature formations|
|WO2011161581A1||13 Jun 2011||29 Dic 2011||Schlumberger Canada Limited||High temperature polymer gels for well treatments and their use|
|WO2012135476A1 *||29 Mar 2012||4 Oct 2012||Prad Research And Development Limited||Methods and compositions to delay viscosification of treatment fluids|
|Clasificación de EE.UU.||166/270, 523/130, 507/203, 507/903, 507/225, 166/294, 507/902, 507/935, 166/295|
|Clasificación cooperativa||Y10S507/902, Y10S507/935, Y10S507/903, C09K8/50|
|14 Ago 1987||AS||Assignment|
Owner name: MARATHON OIL COMPANY, 539 SOUTH MAIN STREET, FINDL
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:SYDANSK, ROBERT D.;REEL/FRAME:004745/0629
Effective date: 19870811
Owner name: MARATHON OIL COMPANY, OHIO
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:SYDANSK, ROBERT D.;REEL/FRAME:004745/0629
Effective date: 19870811
|27 Sep 1988||CC||Certificate of correction|
|23 Sep 1991||FPAY||Fee payment|
Year of fee payment: 4
|28 Sep 1995||FPAY||Fee payment|
Year of fee payment: 8
|26 Dic 1995||REMI||Maintenance fee reminder mailed|
|28 Oct 1999||FPAY||Fee payment|
Year of fee payment: 12